1. Field of the Invention
This invention relates to medical diagnostic tests and, more specifically, to a diagnostic test for evaluating a neurological deficiency in a patient by inducing an involuntary abdominal contraction and obtaining a measurement of pressure generated by the involuntary contraction.
2. Description of the Prior Art
People may experience many different types of neurological deficiencies. One common type, for example, is the iatrogenic neurological deficiency caused by general anesthesia. Another example includes urinary incontinence, where a patient loses either complete or partial bladder control due to nerve damage of some sort. Still another example may be the stroke victim who has lost muscle strength and tone along one side of the body, consequently being unable to contract at least half the muscles which help produce a cough forceful enough to properly clear the respiratory airways.
For example, a patient experiencing urinary incontinence must be properly diagnosed to identify the specific type of incontinence from which the patient suffers. The treatments may be different, depending on the type of incontinence. Therefore, proper diagnosis becomes important at least for that reason.
Stress incontinence is a condition believed to result primarily in older women due to loss of extrinsic support for the pelvic organs and for the neck of the bladder. The tissues of the pelvis and of the distal urethra contain estrogen and progesterone receptors. Following menopause and decrease of the hormones, the tissues of the urethra may lose resiliency and become somewhat flaccid. Under those conditions, any increase in intra-abdominal pressure causes urine in the bladder to be pushed outwardly as resistance in the urethra is overcome, resulting in leakage of urine. This condition is known as stress incontinence and occurs in the absence of contractions by the detrusor muscle of the bladder. Stress incontinence may be responsive to treatment with exogenous estrogens, although this is not an effective treatment for all patients, particularly depending on age. Alternative treatments may include pelvic muscle exercises, a-adrenergic agents, such as phenylpropanolamine, that act on the a-adrenergic receptors along the urethra and increase urethral tone.
The most common cause of urinary incontinence, however, is detrusor hyperreflexia, or hyperactivity of the detrusor muscle. This type of incontinence is believed to result from lack of inhibition of the detrusor muscle due to a decreased detrusor reflex in the brain stem. Nevertheless, in most affected elderly there appears to be no underlying neurological defect. In this condition, treatment may include antispasmodic agents which tend to relax the wall of the bladder.
A typical test employed to distinguish these two types of urinary incontinence is one which increases intra-abdominal pressure so as to, in turn, put pressure on the bladder. The Valsalva maneuver is one such test. This procedure is named after Antonio M. Valsalva, an Italian anatomist of the late seventeenth and early eighteenth centuries. In this technique, the patient generates a muscular contraction of the chest, abdomen and diaphragm in a forced expiration against a closed glottis. This increases pressure within the thoracic cavity and also in the abdominal cavity. The Valsalva maneuver also refers to raising the pressure in the nasopharynx by a forced expiration with the mouth closed and the nostrils pinched, for example, to clear the patency of the Eustachian tubes. Other testing techniques involve having the patient jump up and down to jostle the bladder, or bend down so as to compress the abdomen. Yet another method involves having the patient generate one or more strong voluntary coughs.
It is known, however, that some patients are unable to perform these physical acts. For example, a patient may not be able to jump, or to bend, or to generate a strong voluntary cough. Additionally, there are some patients who will not be correctly diagnosed on the basis of the cough test, perhaps because their coughs are insufficiently strong. Accordingly, there is a need for alternative or supplementary tests that will aid in diagnosing urinary stress incontinence.
As noted above, however, other clinical diagnostic tests also rely on the patient's ability to generate a forceful volitional abdominal contraction or Valsalva maneuver as an identifier of normal neurological and/or muscular function. Many patients, however, are unable to produce a forceful voluntary abdominal contraction or voluntary Valsalva maneuver and the associated diagnosis may be hampered or missed altogether.
A rather complete discussion of methods of evaluating urinary incontinence is found in a February 2006 article by JL Martin et al. entitled “Systematic review and evaluation of methods of assessing urinary incontinence (hereinafter referred to as Systematic review).”
Problems of the Prior Art
One of the problems associated with the prior art techniques is that some patients are unable or are unwilling to perform the physical acts to the extent needed. For example, a patient may not be able to jump, or to bend, or to generate a strong voluntary cough. Some patients may be able to perform these acts, but be unwilling to do so because, in the use of stress incontinence, an involuntary release of urine may be embarrassing or contrary to what is considered proper in society.